Cross reference
Ezekiel 39:15
15 And the passengers that pass through the land, when any seeth a man's bone, then shall he set up a sign by it, till the buriers have buried it in the valley of Hamongog.
Luke 11:44
44 Woe unto you, scribes and Pharisees, hypocrites! for ye are as graves which appear not, and the men that walk over them are not aware of them.